1. Field of the Invention
This invention relates to an inkjet recorder and more particularly to an inkjet print head designed to inject ink droplets onto a recording medium such as a cloth to form image patterns on the cloth.
2. Prior Art
Conventional recording means using ink include an inkjet recording system.
Due to its light weight, possible miniaturization and low noise level, this recording system has enjoyed wide application in the printing/recording field, allowing use of a wide range of recording mediums.
Especially when this recording system is used as an inkjet printer for printing on a cloth, it is very advantageous in that it can represent fine and multicolor patterns on the cloth with clear boundaries of the patterns in a way not obtainable with any other conventional textile printing technique, as well as that it can achieve great cuts in process loads such as engraving involved in a conventional textile printing process.
Therefore, inkjet printing has now attracted attention from the textile industry as a technology to provide for high-quality textile printing on a multi-variety small-lot production basis.
Inkjet recording systems commonly adopted for such textile printing on a commercial basis is of a type wherein an inkjet print head with nozzles is scanned over a cloth in the direction perpendicular to that in which the cloth is fed, while injecting inks from the nozzles to form image patterns on it.
The important problem with the inkjet print head that must be addressed at the present time, when there has been a demand for high productivity and high quality, is how to allow the ink from the inkjet print head to reach the surface of the cloth with accuracy and improve the quality of the image patterns thus printed on it.
To solve this problem, it is very important to improve the ink discharge stability of the inkjet print head, allowing it to discharge ink droplets continuously in a stable state at all times.
However, a conventional inkjet print head of the prior art presents problems with its ink discharge stability such as ink trajectory inaccuracy and ink discharge failure, resulting in improper printing on a recording medium and marked deterioration in the quality of the image patterns formed on the medium.
One of the factors causing these problems is that the recording medium is contaminated with dust, dirt and other foreign matter, which adheres to the nozzles of the inkjet print head and/or their peripheral areas.
Another factor considered as a cause of the problems is that the recording medium is creased or floats, coming into contact or collision with the nozzles of the inkjet print head with resultant damage to them and/or their peripheral areas.
As a countermeasure against such problems, JP-A-5-330041 disclosed the invention of an inkjet print head covered with a masking plate, wherein its ink discharge outlet ports forming a nozzle face is positioned 5 xcexcm to 500 xcexcm inside from the surface of the masking plate.
This prior art has allowed the inkjet print head""s nozzles and their peripheral areas to be protected against contact with the recording medium and adherence of dust, dirt and other foreign matter present on it.
However, the aforementioned prior art inkjet print head with such a masking plate is disadvantageous in that the ink mist generated from the ink upon its discharge from the nozzles and the ink leaked from the nozzles are prone to collect on the nozzle face.
The above disadvantage of this prior art inkjet print head becomes larger as it is designed with the nozzle face positioned further inside from the masking plate surface to avoid the adherence of foreign matter on the recording medium to the nozzles.
In addition, this prior art inkjet print head has the disadvantage that the area formed between the nozzle face and the masking plate is prone to collect any undesired droplets from the cleaning solution used to clean the nozzle face to prevent the clogging of the nozzles after removal of dust and any other foreign matter from them.
The droplets thus collected in between the nozzle face and the masking plate causes problems such as blocking the trajectory of the ink and assembling into larger masses, which reach the surface of the recording medium, significantly deteriorating the quality of the image patterns formed on it.
The above means that this prior art inkjet print head has achieved success in protecting its nozzles by provision of such a masking plate as described above, but at the cost of deterioration in its printing performance.
To eliminate the above-described disadvantages, it is necessary to allow the ink inevitably adhering to the nozzle face and masking plate to detach smoothly from them before collecting on them to have adverse effects on its printing performance.
However, the prior art inkjet print head presented above, although proving its effectiveness in protecting its nozzles against adherence of foreign matter to them, cannot prevent adherence or collection of droplets onto the nozzle face and masking plate.
The invention disclosed herein was made against the background of the prior art involving the above-mentioned technical problems.
Accordingly, it is an object of the present invention to provide an inkjet recording system with an inkjet print head having a masking plate (nozzle protecting plate) of such configuration as to securely protect the nozzle face against contact and collision with a recording medium and adherence of foreign matter present on the medium to it and to prevent the masking plate and nozzle face from collecting droplets of the ink discharged from the print head.
The ultimate object of the present invention is to provide an inkjet print head with nozzles designed to assure smooth and stable discharge of ink from the nozzles onto a recording medium, thereby achieving improved quality of the image patterns formed on the recording medium.
Specifically, the present invention consists in (1) an inkjet print head with an assembly of more than one nozzle, designed to be scanned over a cloth while injecting inks from the nozzles onto the cloth to form image patterns on it, comprising a nozzle protecting plate mounted on the print head at a given distance from the nozzle face, said nozzle protecting plate having an opening or openings formed as a path or paths for discharge of the inks,
(2) an inkjet print head with an assembly of more than one nozzle, designed to be scanned over a cloth while injecting inks from the nozzles onto the cloth to form image patterns on it, comprising a nozzle protecting plate mounted on the print head at a given distance from the nozzle face, said nozzle protecting plate having a slit or slits formed with its longer dimension parallel to the cloth feeding direction as a path or paths for discharge of the inks,
(3) an inkjet print head as specified in (2) above, wherein two or more of said slits are provided in rows,
(4) an inkjet print head as specified in (2), wherein said slit has an area extending downward from the nozzle area,
(5) an inkjet print head as specified in (2), wherein the dimension of said slit perpendicular to the cloth feeding direction ranges from 0.4 mm to 1.5 mm,
(6) an inkjet print head as specified in (1), wherein the distance between said nozzle protecting plate and nozzle face ranges from 0.4 mm to 2.5 mm,
(7) an inkjet print head as specified in (1), wherein said nozzle protecting plate has its top and bottom (along the cloth feeding direction) inclined in one or more directions,
(8) an inkjet print head as specified in (1), wherein said nozzle protecting plate has its surface treated to have a hydrophilic property,
(9) an inkjet print head with an assembly of more than one nozzle, designed to be scanned over a cloth while injecting inks from the nozzles onto the cloth to form image patterns on it, comprising a nozzle protecting plate mounted on the print head at a distance of 0.4 to 2.5 mm from the nozzle face, said nozzle protecting plate having more than one slit formed in rows with its longer dimension parallel to the cloth feeding direction as paths for discharge of the inks, the dimension of said slit perpendicular to the cloth feeding direction ranging from 0.4 mm to 1.5 mm, said slit having an area extended downward from the nozzle area, and said nozzle protecting plate having its top and bottom (along the cloth feeding direction) inclined in one or two directions; and
(10) an inkjet recorder having such an inkjet print head as specified in (1).
The present invention naturally consists in combination of two or more selected from (3) to (8) mentioned above unless such combination departs from the spirit and object of the invention.